The trend toward energy conservation has driven changes in commercial building codes to incorporate weather barriers. For purposes of this application, the term ‘weather barrier’ means a substrate that inhibits or reduces passage of air or vapours (e.g., water), or both. Many of these weather barriers are polyethylene, polytetrafluoroethylene (e.g., TEFLON®), polyvinyl chloride (PVC), thermoplastic polyolefin (such as TYVEK® from DuPont), or other low surface energy organic substrates. For example, a weather barrier may be wrapped over sheathing and under exterior siding to resist air infiltration and water intrusion into a building. To improve efficacy, it is desirable for a weather barrier system to be continuous, i.e., a sealant is used to bridge the weather barrier with a fenestration element.
There are problems associated with conventional sealants. Conventional sealants typically exhibit poor adhesion to polyethylene and other low surface energy substrates. They may require a primer or other surface treatment (such as corona treatment) to achieve adhesion, and surface treatment adds labour intensity and additional cost to the process of applying a weather barrier. Conventional sealants may not be flexible enough to allow for joint movement, for example, during thermal expansion.
Building owners, contractors, architects and consultants want a primerless, flexible sealant that provides a bond between the weather barrier and building substrates, e.g., fenestration substrates to form a continuous, robust weather barrier system. This reduces air leakage and translates to lower energy costs and meeting new energy building codes. Solutions that exist today utilize a primer and do not offer robust adhesion to allow movement between the substrates.